The medial collateral ligament (MCL) is a broad band on the inner side of the knee that stops the joint opening sideways. It is injured when the knee is forced inwards, typically by a tackle to the outside of the knee, a skiing fall or an awkward twist. It causes pain and tenderness along the inner knee, and it has a good blood supply, so most MCL injuries heal well with bracing and rehabilitation and do not need surgery.
Also known as medial collateral ligament sprain, MCL tear, inner knee ligament injury
Anatomy: where the problem is
Front view of the knee. Highlighted in the diagram: medial collateral ligament (MCL).
Symptoms
- Pain and tenderness along the inner side of the knee
- Swelling over the inner knee, usually within a day or two
- Pain when the knee is pushed inwards or twisted
- Stiffness and difficulty fully bending or straightening
- A feeling that the knee might give way sideways in more severe sprains
- Bruising on the inner knee in some cases
Causes and risk factors
- A blow to the outside of the knee, such as a tackle
- A skiing fall with the ski catching an edge
- A sudden twist or change of direction with the foot planted
- Breaststroke kicking, which can strain the ligament over time
- Landing awkwardly from a jump
What the evidence says helps
- MCL injuries are graded from 1 (a mild sprain) to 3 (a complete tear). The grade guides how much protection the knee needs and how long recovery takes.1
- Non-surgical treatment is the first step for isolated MCL injuries of all grades, including complete tears. This means a hinged brace where needed, early movement and progressive strengthening.1
- Clinical guidelines for knee ligament sprains support early movement, weight-bearing as tolerated and structured strengthening over prolonged immobilisation.2
- Surgery is mainly considered when the MCL is torn together with other ligaments, or when the knee remains unstable after rehabilitation.1
Things you can try at home
- In the first few days, protect the knee, use ice for short spells and keep the leg raised when resting
- Walk as comfort allows, using crutches or a brace if you have been given them
- Keep the knee moving gently: avoid keeping it completely still
- Start thigh muscle exercises early, such as tightening the muscle with the leg straight
- Avoid twisting, pivoting and breaststroke until you have been cleared
- Return to sport in stages once the knee is pain-free, strong and stable
When to get urgent help
Contact your GP urgently, call NHS 111, or call 999 in an emergency if you have:
- A knee that is badly swollen, looks deformed or cannot take weight after an injury: go to A&E
- A hot, red, swollen knee with a fever or feeling unwell: get same-day medical help
- A knee that is locked and cannot be straightened: get same-day medical advice
- A hot, swollen, tender calf, especially with breathlessness or chest pain: call 999, as this can be a blood clot
- A pop in the knee with rapid swelling, or a knee that keeps giving way: get it assessed promptly, as other ligaments may be injured
How Apollo can help
We test the stability of the knee to grade the injury and check the other ligaments and the menisci, because combined injuries need a different plan. If we suspect more than an isolated MCL sprain, we refer you for imaging. Rehabilitation moves through protection, restoring movement, rebuilding strength and control, and a staged return to running, cutting and contact. We use VALD testing to compare strength between your legs before you return to sport.
No GP referral needed. Clinics in Sheringham, Coltishall and Norwich.
Related reading
Frequently asked questions
How long does an MCL sprain take to heal?
As a guide, a grade 1 sprain takes one to three weeks, a grade 2 takes around four to six weeks, and a complete (grade 3) tear takes eight to twelve weeks or more. Return to sport depends on strength and stability, not only on time.
Do I need a knee brace for an MCL injury?
Mild sprains usually do not. A hinged brace is often used for more severe sprains to protect the ligament from sideways stress while allowing the knee to bend. Your clinician can advise how long to wear it.
Will I need surgery for a torn MCL?
Usually not. Even complete tears of the MCL on its own generally heal with bracing and rehabilitation. Surgery is considered when other ligaments are torn as well or the knee stays unstable.
References
- Wijdicks CA, Griffith CJ, Johansen S, Engebretsen L, LaPrade RF (2010). Injuries to the Medial Collateral Ligament and Associated Medial Structures of the Knee. The Journal of Bone and Joint Surgery-American Volume 92:1266-1280. View source
- Logerstedt DS, et al. (2017). Knee Stability and Movement Coordination Impairments: Knee Ligament Sprain Revision 2017. Journal of Orthopaedic & Sports Physical Therapy 47:A1-A47. View source
This page is general information, not a diagnosis or a substitute for medical advice. If you are worried about your symptoms, speak to your GP or a registered healthcare professional. Content prepared from the sources above, November 2026.
